ASTM A 182 Stainless Steel 1 inch Class 300Rf Flat Welding Flange

Pipe flanges are manufactured in all the different materials like stainless steel, cast iron, aluminium, brass, bronze, plastic etc. but the most used material is forged carbon steel and have machined surfaces.

In addition, flanges, like fittings and pipes, for specific purposes sometimes internally equipped with layers of materials of a completely different quality as the flanges themselves, which are "lined flanges".

The material of a flange, is basically set during the choice of the pipe, in most cases, a flange is of the same material as the pipe.

All flanges, discussed on this website fall under the ASME en ASTM standards, unless otherwise indicated. ASME B16.5 describes dimensions, dimensional tolerances etc. and ASTM the different material qualities.

The most used flange types are:

Common types of pipeline flange faces

Flanges provide the necessary connections to link pipelines. Faces are the mating surface of a flange.Different types of flange faces are used as the contact surfaces to seat the sealing gasket material. ASME B16.5 and B16.47 define various types of flange facings, including the raised face, the large male and female facings which have identical dimensions to provide a relatively large contact area.Flange faces have to be smooth enough to ensure a tight, leak-free seal for bolted flanges.

Bolted Flange connections

A bolted flange connection is a complex combination of many factors (Flange, Bolts, Gaskets, Process, Temperature, Pressure, Medium). All these various elements are interrelated and depend upon one another to achieve a successful result.
The reliability of the flanged joint depends critically upon competent control of the joint making process.

Some other Disadvantages of flange connections..

• Each flange connection can leak (some people claim that a flange connection is never 100 percent leak proof).
• Flanged pipe systems need much more space (just think of a pipe rack).
• Insulation of flanged pipe systems is more expensive (special flange caps).

Of course, flange connections have great benefits; some examples..

• A new line can contain multiple pipe spools and can be manufactured in a workshop.
• This pipe spools can be assembled in the plant without the need to be welded.
• NDO (X-ray, Hydro test etc.) in the plant is not necessary, because this has been done in the workshop.
• Blasting and painting in the plant is not necessary, because even this has been done in a workshop
  (only paint damages during installation should be repaired).

What is the difference between a RTJ, FF, and RF flange on seals and thermowells?

The raised face, RF, is the standard process connection on our third party seals and thermowells. Both have options for a RTJ and FF type flange connections. The Raised Face (RF) is the most common type used in process plant applications.
The gasket surface of the flange is raised above the bolting circle face. A Ring-type Joint (RTJ) can also have a raised gasket face with the difference being the ring groove machined in this face.
This groove will accommodate a steel ring gasket for flange mating. The Flat Face, FF, flange has a gasket surface that is in the same plane as the bolting circle face.
None of these three flange types are interchangeable between types, i.e. RTJ flange cannot be mated to a RF flange. ​

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